With release of patch 8.3 on retail, not only you will have to worry about getting the appropriate gear for your character, but also now you’ll have to hope it will get Corrupted by the Old Gods.
What is Corruption, you ask? It is a new modifier that you can get on items from activities related to the new patch. Those activities are Mythic Keystones, new raid, new Old Gods invasions, etc. It brings new positive effects at the cost of negative debuffs that can occur during your fights.
Let’s break down the positives first. As your items gets corrupted, you can get one of the following effects:
• Your Avoidance is increased by an amount equal to X% of your Haste.
• Increases Haste you gain from all sources by X%.
• Increases Mastery you gain from all sources by X%.
• Increases Critical Strike you gain from all sources by X%.
• Increases Versatility you gain from all sources by X%.
• X% of total Health Regeneration now continues during Combat.
• Increases healing received from all sources by X%.
• Increases Leech by X%.
• Increases damage you deal with Critical Strikes by X%.
• Reduces damage taken from periodic effects by X%.
• Your spells and abilities have a chance to grant you a Flash of Clarity, reducing the cooldown of your next 3 spells cast by 2 sec.
There are three tiers of corruption on item, and depending on the tier your effects will be stronger, but you will also get more corruption:
• Tier 1 – 5-10 Corruption
• Tier 2 – 12-17 Corruption
• Tier 3 – 20-25 Corruption
The amount of corruption you get in the respective tiers is random between the lowest and highest number. And, depending on your character’s total corruption amount, you’ll get different debuffs. You could be slowed down, may spawn an AOE zone that will damage you, have a chance to summon a thing that will follow you at set speed, and your damage taken could be increased and healing reduced by a percentage. And all debuffs scale with total corruption your character isn’t resisted to.
So, let’s summarize. Not only do you have to get an item to be corrupted, you also want to get a certain effect that synergizes with your character AND hope that the item will get as less corruption as possible, within respective tiers. We hope that explains the new corruption system.